Networks based on the Long Term Evolution, LTE, specifications, as promulgated by the Third Generation Partnership Project, 3GPP, use two kinds of reference signals: Cell-specific Reference Signals or CRS, and Demodulation Reference Signals or DMRS, which are also denoted as DM-RS. CRS span the complete “system” bandwidth involved and they are “always on.” In contrast, DMRS span only the scheduled bandwidth to which they pertain and they are only transmitted when transmitting data.
The advantage of reference signals that are always transmitted is that a wireless communication device, referred to as a UE or User Equipment in 3GPP parlance, can rely on their presence. Drawbacks associated with CRS include a high network energy consumption because CRS are even transmitted if no data are transmitted. CRS also create unnecessary interference because they are transmitted even if not needed.
See FIG. 1, which illustrates an example system bandwidth and the transmission of CRS and DMRS within the system bandwidth. In an Orthogonal Frequency Division Multiplex, OFDM, example applicable to the LTE context, the system bandwidth comprises a plurality of spaced-apart, narrow-band subcarriers that, in the aggregate, span the system bandwidth. Each subcarrier taken at each transmission time may be regarded as Resource Element, or RE, and FIG. 1 can be understood as depicting some portion of an OFDM time-frequency grid, with CRS and DMRS being transmitted on specific subcarriers at specific times. More particularly, one sees regular transmissions of CRS across the system bandwidth, along with the transmission of DMRS in conjunction with data transmission on scheduled resources.
In LTE, the DRMS sequence element transmitted on a given subcarrier depends on the position of the subcarrier within the overall plurality of subcarriers constituting the overall system bandwidth. For example, with the subcarriers are numbered from 0 to N, the sequence element associated with the m-th subcarrier depends on the value of m. This approach can be understood as a “global” numbering scheme that applies to the system bandwidth and, importantly, LTE UEs support the full system bandwidth.
In more detail, in LTE, for any of the antenna ports p∈{7,8, . . . , v+6}, the reference-signal sequence r(m) used for DMRS on subcarrier m within the downlink, DL, system bandwidth NRBmaxDL resource blocks, is defined by
            r      ⁡              (        m        )              =                            1                      2                          ⁢                  (                      1            -                          2              ·                              c                ⁡                                  (                                      2                    ⁢                    m                                    )                                                              )                    +              j        ⁢                  1                      2                          ⁢                  (                      1            -                          2              ·                              c                ⁡                                  (                                                            2                      ⁢                      m                                        +                    1                                    )                                                              )                      ,          ⁢      m    =          {                                                                  0                ,                1                ,                …                ⁢                                                                  ,                                                      12                    ⁢                                          N                      RB                                              max                        ,                        DL                                                                              -                  1                                                                                                      normal                  ⁢                                                                          ⁢                  cyclic                  ⁢                                                                          ⁢                  prefix                                ⁢                                                                                                                                          0                ,                1                ,                …                ⁢                                                                  ,                                                      16                    ⁢                                          N                      RB                                              max                        ,                        DL                                                                              -                  1                                                                                    extended                ⁢                                                                  ⁢                cyclic                ⁢                                                                  ⁢                prefix                                                    .            
The pseudo-random sequence c(i) is defined by a length-31 Gold sequence.
The output sequence c(n) of length MPN, where n=0.1, MPN−1, is defined byc(n)=(x1(n+NC)+x2(n+NC))mod2x1(n+31)=(x1(n+3)+x1(n))mod2x2(n+31)=(x2(n+3)+x2(n+2)+x2(n+1)+x2(n))mod2
where NC=1600 and the first m-sequence shall be initialized with x1(0)=1,x1(n)=0,n=1,2, . . . , 30. The initialization of the second m-sequence is denoted by cinit=Σi=030x2(i)·2i with the value depending on the application of the sequence.
The pseudo-random sequence generator shall for DMRS in LTE be initialized withcinit=(└ns/2┘+1)·(2nID(nSCID)+1)·216+nSCID at the start of each subframe.
The quantities nID(i), i=0,1, are given by                nID(i)=NIDcell if no value for nIDDMRSi is provided by higher layers or if DCI format 1A, 2B or 2C is used for the DCI associated with the PDSCH transmission        nID(i)=nIDDMRSi otherwise where this value is indicated in the downlink control information used to schedule the PDSCH. Here, “DCI” denotes Downlink Control Information, and “PDSCH” denotes Physical Downlink Shared Channel.        
It is recognized herein that certain complications arise concerning the generation and use of DRMS signals in the context of NR, where “NR” denotes the New Radio standard at issue in the ongoing development of next-generation communication networks, which are also referred to as 5G networks. NR contemplates wide system bandwidths—e.g., bandwidths of 1 GHz or more—and not every terminal operating in an NR system will have the capability to operate over the complete system bandwidth
NR will, therefore, provide support for terminals capable of supporting only a fraction of the system bandwidth. For example, the network configures a portion of the system bandwidth for use by the terminal, referred to as terminal's configured bandwidth, and then uses bandwidth within the configured bandwidth for scheduling the terminal, referred to as the terminal's scheduled bandwidth.
A terminal may perform access to an NR carrier by detecting a synchronization signal and broadcast channel and performing a subsequent random access. After random access, the network could configure the terminal to a new frequency relative to the frequency used for initial access. This approach does not require the terminal to know the system bandwidth or know where its configured bandwidth lies within the system bandwidth.